How Do Young Soccer Players Train? A 5-Year Analysis of Weekly Training Load and its Variability Between Age Groups in an Elite Youth Academy

ABSTRACT

Connolly, DR, Stolp, S, Gualtieri, A, Ferrari Bravo, D, Sassi, R, Rampinini, E, and Coutts, AJ. How do young soccer players train? A 5-year analysis of weekly training load and its variability between age groups in an elite youth academy. J Strength Cond Res 38(8): e423-e429, 2024-The aim of this study was to quantify the session rating of perceived exertion (sRPE), duration, and training load accrued across typical training weeks undertaken by youth soccer players. Differences between starters, nonstarters, and variations in training load variables were also investigated. Data were collected from 230 elite youth players in 4 age groups (U15, U16, U17, and U19) during 5 competitive seasons. Mixed models were used to describe variation between age groups and compare starters with nonstarters, with season as a fixed covariate effect. Week-to-week variation in training load was expressed as the percentage coefficient of variation. The main findings may be used to highlight a significant effect of age and playing status on training intensity, duration, and internal training load. Weekly training load increased progressively from the U15 to U17, with significant differences between each age group (p < 0.03). Lower mean weekly perceived intensity (sRPE) was noted in U15 when compared with the older age groups (4.2 vs. 4.6-4.9 arbitrary unit for U16 to U19, p < 0.001). Low weekly training load variation was observed across the different phases of the season in each age group, with the preseason exhibiting the greatest variance (3.6-6.2%). Differences in the training load are likely more attributable to changes in training duration rather than sRPE. Control of session duration seems to play an important role when aiming to control load in the academy environment, and practitioners should closely monitor the differences in duration and load being recorded between starters and nonstarters.

Toward a New Conceptual Approach to "Intensity" in Soccer Player's Monitoring: A Narrative Review

ABSTRACT

Pillitteri, G, Clemente, FM, Petrucci, M, Rossi, A, Bellafiore, M, Bianco, A, Palma, A, and Battaglia, G. Toward a new conceptual approach to "intensity" in soccer player's monitoring: A narrative review. J Strength Cond Res 37(9): 1896-1911, 2023-In the last decade, monitoring physiological and match-related demands in soccer has become an increasingly common practice in sports sciences. One of the great challenges during monitoring process is the identification of key indicators that permit to generalize evidence and sustain decision-making process during training prescription. Actually, one of the major debates in the scientific community and among practitioners is the identification of the "intensity" concept. Defining a given training session or exercise based on "intensity" is difficult due to the fact that a huge amount of indicators are available (related both to the performed activities and to the athletes' psychophysiological responses). These indicators can lead to specific outcomes with different interpretations. The current narrative review aims to discuss the different measures approaches used in soccer to describe the intensity for both internal and external demands. In addition, a second purpose of this review is to propose general recommendations for combining intensity indicators with the aim of defining an overall intensity score of a training session or drill.

Resultant equations for training load monitoring during a standard microcycle in sub-elite youth football: a principal components approach

Applying data-reduction techniques to extract meaningful information from electronic performance and tracking systems (EPTS) has become a hot topic in football training load (TL) monitoring. The aim of this study was to reduce the dimensionality of the internal and external load measures, by a principal component approach, to describe and explain the resultant equations for TL monitoring during a standard in-season microcycle in sub-elite youth football. Additionally, it is intended to identify the most representative measure for each principal component. A principal component analysis (PCA) was conducted with a Monte Carlo parallel analysis and VariMax rotation to extract baseline characteristics, external TL, heart rate (HR)-based measures and perceived exertion. Training data were collected from sixty sub-elite young football players during a 6-week training period using 18 Hz global positioning system (GPS) with inertial sensors, 1 Hz short-range telemetry system, total quality recovery (TQR) and rating of perceived exertion (RPE). Five principal components accounted for 68.7% of the total variance explained in the training data. Resultant equations from PCA was subdivided into: (1) explosiveness, accelerations and impacts (27.4%); (2) high-speed running (16.2%); (3) HR-based measures (10.0%); (4) baseline characteristics (8.3%); and (5) average running velocity (6.7%). Considering the highest factor in each principal component, decelerations (PCA 1), sprint distance (PCA 2), average HR (PCA 3), chronological age (PCA 4) and maximal speed (PCA 5) are the conditional dimension to be considered in TL monitoring during a standard microcycle in sub-elite youth football players. Current research provides the first composite equations to extract the most representative components during a standard in-season microcycle in sub-elite youth football players. Futures research should expand the resultant equations within training days, by considering other well-being measures, technical-tactical skills and match-related contextual factors.

Methods of Monitoring Internal and External Loads and Their Relationships with Physical Qualities, Injury, or Illness in Adolescent Athletes: A Systematic Review and Best-Evidence Synthesis

BACKGROUND

With the increasing professionalisation of youth sports, training load monitoring is increasingly common in adolescent athletes. However, the research examining the relationship between training load and changes in physical qualities, injury, or illness in adolescent athletes is yet to be synthesised in a systematic review.

OBJECTIVE

The aim of this review was to systematically examine the research assessing internal and external methods of monitoring training load and physical qualities, injury, or illness in adolescent athletes.

METHODS

Systematic searches of SPORTDiscus, Web of Science, CINAHL and SCOPUS were undertaken from the earliest possible records to March 2022. Search terms included synonyms relevant to adolescents, athletes, physical qualities, injury, or illness. To be eligible for inclusion, articles were required to (1) be original research articles; (2) be published in a peer-reviewed journal; (3) include participants aged between 10 and 19 years and participating in competitive sport; (4) report a statistical relationship between a measure of internal and/or external load and physical qualities, injury or illness. Articles were screened and assessed for methodological quality. A best-evidence synthesis was conducted to identify trends in the relationships reported.

RESULTS

The electronic search yielded 4125 articles. Following screening and a review of references, 59 articles were included. The most commonly reported load monitoring tools were session ratings of perceived exertion (n = 29) and training duration (n = 22). Results of the best-evidence synthesis identified moderate evidence of positive relationships between resistance training volume load and improvement in strength, and between throw count and injury. However, evidence for other relationships between training load and change in physical qualities, injury, or illness were limited or inconsistent.

CONCLUSIONS

Practitioners should consider monitoring resistance training volume load for strength training. Additionally, where appropriate, monitoring throw counts may be useful in identifying injury risk. However, given the lack of clear relationships between singular measures of training load with physical qualities, injury, or illness, researchers should consider multivariate methods of analysing training load, as well as factors that may mediate the load-response relationship, such as maturation.

Effects of Playing Position and Contextual Factors on Internal Match Loads, Post-Match Recovery and Well-Being Responses of Elite Male Water Polo Players

This study aimed to investigate the effects of playing position and contextual factors (match outcome, final score difference, match location, travel duration, number of scored and conceded goals) on the internal match load, players' perceived recovery and players' well-being. The session-RPE (s-RPE), Perceived Recovery Scale (PRS) and Hooper Index (HI) of 17 male elite water polo players were monitored during all matches (regular season and play-out) of the 2021/22 Italian Serie A1 championship. Three separate, mixed linear models for repeated measures showed significant main effects: drawn compared to won matches led to higher s-RPE values (mean ± SE = 277 ± 17.6 vs. 237.3 ± 20.6), while longer travel duration (estimate = -0.148) and goals scored (estimate = -3.598) led to lower s-RPE values; balanced compared to unbalanced matches led to higher PRS values (mean ± SE = 6.8 ± 0.3 vs. 5.1 ± 0.4), while playing time (estimate = -0.041) and goals scored (estimate = -0.180) led to lower PRS values; higher scores of the HI were registered for regular season compared to the play-out (mean ± SE = 15.6 ± 0.9 vs. 13.5 ± 0.8). This study marks the importance of ecological and non-invasive monitoring tools to assess internal match load, recovery and the well-being of elite water polo players.

Strength and Power Performance Changes During an In-Season Resistance Training Program in Elite Futsal Players: A Case Study

In this study, we aimed to analyze (i) the strength and power changes after resistance training (RT) in elite futsal players, and (ii) the associations between the session rate of perceived exertion (sRPE) and perceived total quality recovery (TQR), and the sRPE and TQR with the volume load of the RT program. Ten elite futsal players (24.8 ± 5.4 years; 76.2 ± 7.1 kg; 1.77 ± 0.05 m) performed an in-season 8-week RT program twice per week. RT consisted of 2-3 sets x 3-6 reps at 45-65% of one-repetition maximum (1RM) with maximal velocities in the full squat and complementary exercises with the same volume. We assessed the TQR before every session, while the sRPE was calculated after each RT session. One week before and after the intervention, we measured the countermovement jump (CMJ) height, isometric hip adduction strength (IHAS), 1RM, and peak power (PP) in the full squat progressive loading test. After the 8-week training program, there was a significant improvement in most outcomes, yet the gains (%Δ) remained below the minimal detectable change (MDC), except for IHAS (CMJ: p < 0.05, %Δ = 6.7, MDC% = 7.2; IHAS: p < 0.001, %Δ = 19.1, MDC% = 14.6; 1RM: p > 0.05, %Δ = 9.2, MDC% = 21.5; PP: p < 0.05; %Δ = 14.4, MDC% = 22.4). We also found a significant negative correlation between TQR and the sRPE (r = -0.45, p < 0.001). Our data suggest that RT based on low-volume and low-to-moderate loads may not produce a sufficient stimulus to induce meaningful dynamic strength and power gains in elite futsal players, although it improves isometric strength. Furthermore, monitoring TQR before sessions may show coaches how the elite futsal player will perceive the session's intensity.

Weekly Training Load across a Standard Microcycle in a Sub-Elite Youth Football Academy: A Comparison between Starters and Non-Starters

Compensatory training sessions have been highlighted as useful strategies to solve the differential weekly training load between the players' starting status. However, the influence of the players' starting status is still understudied in sub-elite youth football. Thus, the aim of this study was to compare the weekly training load on a standard microcycle in starters and non-starters of a sub-elite youth football academy. The weekly training load of 60 young sub-elite football players was monitored during a 6-week period using an 18 Hz global positioning system (GPS), 1 Hz telemetry heart rate, rating of perceived exertion (RPE), and total quality recovery (TQR). The total distance (TD) covered presented a significant difference between starters and non-starters with a moderate effect (t = -2.38, Δ = -428.03 m, p = 0.018, d = 0.26). Training volume was higher in non-starters than in starter players (TD_Starters = 5105.53 ± 1684.22 vs. TD_Non-starters = 5533.56 ± 1549.26 m). Significant interactive effects were found between a player's starting status, playing time, and session duration in overall training load variables for within (F = 140.46; η² = 0.85; p < 0.001) and between-subjects (F = 11.63 to 160.70; η² = 0.05 to 0.76; p < 0.001). The player's starting status seems to only influence the training volume in sub-elite youth football, unless one considers the covariance of the playing time and session duration. Consequently, coaches should prioritize complementary training to equalize training volume and emphasize similar practice opportunities for non-starters. Future studies should evaluate the gap between training and match load, measuring the impact of recovery and compensatory sessions.

Monitoring Psychometric States of Recovery to Improve Performance in Soccer Players: A Brief Review

In order to maximize adaptations and to avoid nonfunctional overreaching syndrome or noncontact injury, coaches in high-performance sports must regularly monitor recovery before and after competitions/important training sessions and maintain well-being status. Therefore, quantifying and evaluating psychometric states of recovery during the season in sports teams such as soccer is important. Over the last years, there has been substantial growth in research related to psychometric states of recovery in soccer. The increase in research on this topic is coincident with the increase in popularity obtained by subjective monitoring of the pre-fatigue state of the players before each training sessions or match with a strong emphasis on the effects of well-being or recovery state. Among the subjective methods for players’ control, the Hooper index (HI) assesses the quality of sleep during the previous night, overall stress, fatigue, and delayed-onset muscle soreness. Additionally, the total quality of recovery (TQR) scale measures recovery status. The HI and TQR recorded before each training session or match were affected by the variability of training load (TL) and influenced the physical and technical performances, and the affective aspects of soccer players. Researchers have recommended wellness monitoring soccer players’ psychometric state of recovery before each training session or match in order to detect early signs of fatigue and optimize high-level training performance. This method allows for better detecting signs of individual fatigue and allows coaches to adapt and readjust the TL, and avoid physical and technical gaps in order to improve the performance of soccer players.

Emotional Intelligence in Ultra-Marathon Runners: Implications for Recovery Strategy and Stress Responses during an Ultra-Endurance Race

The aim of this research was to investigate the role of trait emotional intelligence (EI) in recovery stress states in a mountain ultra-marathon (MUM) race. Recovery stress states of 13 finishers were assessed before, during, and immediately after the end of an extreme MUM, whereas emotional intelligence was assessed 2 days before the MUM race. Temporal evolutions of recovery stress states were examined. Stress states increased after the race whereas recovery states decreased in all participants. In addition, recovery states were influenced by the trait EI level assessed before the competition. Results supported the hypothesis that trait EI tends to have a positive effect by boosting recovery strategies. In this perspective, trait EI could have a protective role against stress and improve pre-competition mental preparation. High scores of trait EI (in comparison to low scores of trait EI) could have helped athletes to increase recovery states in order to improve their psychological adaptation to one of the most difficult races in the world.

Monitoring Elite Youth Football Players' Physiological State Using a Small-Sided Game: Associations With a Submaximal Running Test

PURPOSE

To examine the utility of a standardized small-sided game (SSG) for monitoring within-player changes in mean exercise heart rate (HRex) when compared with a submaximal interval shuttle-run test (ISRT).

METHODS

Thirty-six elite youth football players (17 [1] y) took part in 6 test sessions across an in-season period (every 4 wk). Sessions consisted of the ISRT (20-m shuttles, 30″:15″ work:rest ratio, 70% maximal ISRT) followed by an SSG (7v7, 80 × 56 m, 6 min). HRex was collected during both protocols, with SSG external load measured as high-speed running distance (>19.8 km·h-1) and acceleration distance (>2 m·s-2). Data were analyzed using linear mixed-effect models.

RESULTS

Controlling for SSG external load improved the model fit describing the SSG-ISRT HRex relationship (χ2 = 12.6, P = .002). When SSG high-speed running distance and SSG acceleration distance were held constant, a 1% point change in SSG HRex was associated with a 0.5% point change in ISRT HRex (90% CI: 0.4 to 0.6). Inversely, when SSG HRex was held constant, the effects of a 100-m change in SSG high-speed running distance and a 21-m change in SSG acceleration distance on ISRT HRex were -1.0% (-1.5 to -0.4) and -0.6% points (-1.1 to 0.0), respectively.

CONCLUSIONS

An SSG can be used to track within-player changes in HRex for monitoring physiological state. Given the uncertainty in estimates, we advise to only give meaning to changes in SSG HRex >2% points. Additionally, we highlight the importance of considering external load when monitoring SSG HRex.

Differences in External and Internal Load in Elite Youth Soccer Players within Different Match Timing Zones

The aim of this study was to determine and analyze the differences between the players’ internal (IL) and external load (EL) in different time zones (T1: 0–45 min, T2: 45–70 min, T3: 0–70 min, T4: 70–90 min, T5: 45–90 min, and T6: 0–90 min) in elite youth soccer matches (U17–19 age category). The monitored group comprised elite youth soccer players (n = 66; age = 17.5 ± 1.2 years; body height = 178.5 ± 8.7 cm; body mass = 70.4 ± 6.3 kg). Multivariate analysis of variances was used to compare the following variables: relative total distance covered (TDCrel), distance covered in different speed zones (Z1–Z6), high-metabolic load distance (HMLD), maximum running speed (Smax), number of acceleration (ACC) and deceleration (DCC) entries in different speed zones (Z1, Z2, Z3), and maximum heart rate (HRmax). Results revealed significant differences (p < 0.05) in the first 70 min (T3) compared to the last 20 min of the match (T4) in the following: TDCrel was higher, up to 6.6% (123.09 ± 9.48 vs. 115.03 ± 9.42 m.min−1); distance in Z5 (22.4%, 6.08 ± 1.82 vs. 4.72 ± 1.72 m.min−1); Z4 (18.6%, 20.15 ± 4.82 vs. 16.40 ± 3.48 m.min−1); Z3 (10.4%, 53.06 ± 47.52 m.min−1); and HMLD (16.1%, 34.86 ± 5.67 vs. 29.26 ± 5.11 m.min−1). We also found higher running performance in the first half (T1) than in the second half (T5) in the following parameters: TDCrel, Z5, Z4, ACCZ1, ACCZ2, and DCCZ1. With progressive time (in T4) we found a significant decrease in physical running performance, probably due to fatigue, which can lead to potential injury or losing in a match. The results of this study may provide helpful information in developing training strategies for coaches and in the set-up of plan for potential substitution of exhausted players mainly for the last 20 min of a match (T4). The present results are expressed as a relative value and should be compared with other study results with irregular timing zones.

A Practical Approach to Assessing Physical Freshness: Utility of a Simple Perceived Physical Freshness Status Scale

Background: Monitoring physical freshness is essential in assessing athletes’ conditions during training periods, training sessions, or competitions. To date, no single physical freshness scale has been successfully validated against training load variables and widely used scales measuring different facets of physical freshness. Objective: In this study, we develop and test the practical utility of a perceived physical freshness (RPF) scale to monitor the condition of the athletes and to prevent excessive fatigue and insufficient recovery during training sessions or competitions. Methods: Sixteen professional male soccer players (mean ± SD age 26 ± 4 years) were enrolled. Training load (TL), monotony, strain, rate of perceived exertion (RPE), well-being indices (sleep, stress, fatigue, and muscle soreness), total quality recovery (TQR) and RPF were determined each day for two weeks of training, including a week intensified training (IW) and a week taper (TW). The validity of the RPF scale was assessed by measuring the level of agreement of a player’s perceived physical freshness relative to their TL variables, recovery state and well-being indices during each training phase (IW and TW) and during the overall training period (TP). Results: RPF increased during the TW compared to IW (ES = 2.31, p < 0.001, large). For the TP, IW and TW, weekly RPF was related to weekly TL (r = −0.81, r = −0.80, r = −0.69, respectively), well-being (r = −0.91, r = −0.82, r = −0.84, respectively) and TQR (r = 0.76, r = 0.91, r = 0.52, respectively), all p < 0.01. For the TP, IW and TW, daily RPF was related to TL (r = −0.75, r = −0.66, r = −0.70, respectively), well-being (r = −0.84, r = −0.81, r = −0.78, respectively) and TQR (r = 0.82, r = 0.81, r = 0.75, respectively), all p < 0.01. Conclusions: RPF was effective for evaluating the professional soccer players’ physical freshness and may be a strategy for coaches to monitor the physical, psycho-physiological, and psychometric state of the players before training session or matches.

Practices of Strength and Conditioning Coaches: A Snapshot From Different Sports, Countries, and Expertise Levels

ABSTRACT

Weldon, A, Duncan, MJ, Turner, A, LaPlaca, D, Sampaio, J, and Christie, CJ. Practices of strength and conditioning coaches: a snapshot from different sports, countries, and expertise levels. J Strength Cond Res 36(5): 1335-1344, 2022-This study describes the practices of strength and conditioning coaches (SCCs) from different sports, countries, and expertise levels. One hundred fifty-six SCCs (31.9 ± 8.9 years old) completed an online survey, consisting of 40 questions (36 fixed response and 4 open-ended), with 8 sections as follows: (a) background information, (b) muscular strength and power development, (c) speed development, (d) plyometrics, (e) flexibility development, (f) physical testing, (g) technology use, and (h) programming and any additional comments. Responses were received from 48 sports and 17 countries. This study provides exploratory evidence incorporating responses primarily in soccer (45%), track and field (30%), volleyball (23%), golf (17%), and tennis (17%). A bachelor's degree or higher were held by 99% of SCCs, of which 94% were in a sports science-related field, and 71% held a strength and conditioning related certification or accreditation. Periodization strategies and physical testing were used by 96% and 94% of SCCs respectively. The hang clean (82%), power clean (76%), and clean high pull (63%) were the most prescribed Olympic weightlifting exercises. Multiple hops/lunges (84%) were the most prescribed plyometrics exercises. For open-ended questions, 40% of SCCs wanted to integrate more technology into their programs and 30% believed technology will be the main future trend. Strength and conditioning coaches from different sports, countries, and expertise levels can use the information presented in this study to review their current practices and provide a source of new ideas for diversifying or modifying future practices.

Effects of Chronological Age, Relative Age, and Maturation Status on Accumulated Training Load and Perceived Exertion in Young Sub-Elite Football Players

The aims of this study were 1) to analyze the influence of chronological age, relative age, and biological maturation on accumulated training load and perceived exertion in young sub-elite football players and 2) to understand the interaction effects amongst age grouping, maturation status, and birth quartiles on accumulated training load and perceived exertion in this target population. A 6-week period (18 training sessions and 324 observation cases) concerning 60 young male sub-elite football players grouped into relative age (Q1 to Q4), age group (U15, U17, and U19), and maturation status (Pre-peak height velocity (PHV), Mid-PHV, and Post-PHV) was established. External training load data were collected using 18 Hz global positioning system technology (GPS), heart-rate measures by a 1 Hz short-range telemetry system, and perceived exertion with total quality recovery (TQR) and rating of perceived exertion (RPE). U17 players and U15 players were 2.35 (95% CI: 1.25–4.51) and 1.60 (95% CI: 0.19–4.33) times more likely to pertain to Q1 and Q3, respectively. A negative magnitude for odds ratio was found in all four quartile comparisons within maturation status (95% CI: 6.72–0.64), except for Mid-PHV on Q2 (95% CI: 0.19–4.33). Between- and within-subject analysis reported significant differences in all variables on age group comparison measures (F = 0.439 to 26.636, p = 0.000 to 0.019, η2 = 0.003–0.037), except for dynamic stress load (DSL). Between-subject analysis on maturity status comparison demonstrated significant differences for all training load measures (F = 6.593 to 14.424, p = 0.000 to 0.037, η2 = 0.020–0.092). Interaction effects were found for age group x maturity band x relative age (Λ Pillai’s = 0.391, Λ Wilk’s = 0.609, F = 11.385, p = 0.000, η2 = 0.391) and maturity band x relative age (Λ Pillai’s = 0.252, Λ Wilk’s = 0.769, F = 0.955, p = 0.004, η2 = 0.112). Current research has confirmed the effects of chronological age, relative age, and biological maturation on accumulated training load. Perceived exertion does not seem to show any differences concerning age group or maturity status. Evidence should be helpful for professionals to optimize the training process and young football players’ performance.

External load differences between elite youth and professional football players: ready for take-off?

This study examines differences in weekly load between the first (FT) and the under 19 team (U19) within a professional football setting. Data were collected in 11 FT and 9 U19 players (2016-2017 season). FT data was divided into weeks with (FT-M1) or without (FT-M0) a mid-week match. Indicators were total distance (TD) and TD at 12-15, 15-20, 20-25 and >25 km‧h^-1 and were analysed as external load (m), intensity (m‧min^-1) and load monotony (a.u.). TD-based load was higher for U19 compared to FT-M0 (very likely moderate) and FT-M1 (likely large). Differences at higher velocities were substantially less (trivial to possibly small), with TD >25 km‧h^-1 being lower than FT-M0 (very likely moderate) and FT-M1 (likely small). All intensity indicators were lower for U19 (likely small to almost certainly large). Load monotony was higher compared to FT-M1 (possibly small to almost certainly very large). Compared to FT-M0, monotony was higher for TD (possibly very large) and TD >25 km‧h^‑1 (possibly moderate) but lower for TD 12-15 (possibly small) and 15-20 km‧h^‑1 (likely moderate). So, despite higher weekly external loads at low velocity for elite youth players, external intensity and load variation increases when these players may transition to professional football.

Submaximal Fitness Tests in Team Sports: A Theoretical Framework for Evaluating Physiological State

Team-sports staff often administer non-exhaustive exercise assessments with a view to evaluating physiological state, to inform decision making on athlete management (e.g., future training or recovery). Submaximal fitness tests have become prominent in team-sports settings for observing responses to a standardized physical stimulus, likely because of their time-efficient nature, relative ease of administration, and physiological rationale. It is evident, however, that many variations of submaximal fitness test characteristics, response measures, and monitoring purposes exist. The aim of this scoping review is to provide a theoretical framework of submaximal fitness tests and a detailed summary of their use as proxy indicators of training effects in team sports. Using a review of the literature stemming from a systematic search strategy, we identified five distinct submaximal fitness test protocols characterized in their combinations of exercise regimen (continuous or intermittent) and the progression of exercise intensity (fixed, incremental, or variable). Heart rate-derived indices were the most studied outcome measures in submaximal fitness tests and included exercise (exercise heart rate) and recovery (heart rate recovery and vagal-related heart rate variability) responses. Despite the disparity between studies, these measures appear more relevant to detect positive chronic endurance-oriented training effects, whereas their role in detecting negative transient effects associated with variations in autonomic nervous system function is not yet clear. Subjective outcome measures such as ratings of perceived exertion were less common in team sports, but their potential utility when collected alongside objective measures (e.g., exercise heart rate) has been advocated. Mechanical outcome measures either included global positioning system-derived locomotor outputs such as distance covered, primarily during standardized training drills (e.g., small-sided games) to monitor exercise performance, or responses derived from inertial measurement units to make inferences about lower limb neuromuscular function. Whilst there is an emerging interest regarding the utility of these mechanical measures, their measurement properties and underpinning mechanisms are yet to be fully established. Here, we provide a deeper synthesis of the available literature, culminating with evidence-based practical recommendations and directions for future research.

Influence of Well-Being Indices and Recovery State on the Technical and Physiological Aspects of Play During Small-Sided Games

ABSTRACT

Selmi, O, Gonçalves, B, Levitt, DE, Ouergui, I, Sampaio, J, and Bouassida, A. Influence of well-being indices and recovery state on the technical and physiological aspects of play during small-sided games. J Strength Cond Res 35(10): 2802-2809, 2021-Soccer players performing at high level are frequently exposed to periods of intense training, which can induce substantial stress and fatigue. These high-intensity stimuli likely lead to a lower state of well-being and poor recovery and, consequently, may affect players' performance. This study aimed to assess the influence of well-being indices (i.e., self-ratings of sleep, stress, fatigue, and delayed onset muscle soreness [DOMS]) and the total quality of recovery (TQR) on technical and physiological measures during soccer small-sided games (SSGs). Twenty male professional soccer players (age: 25.1 ± 1.0 years) performed four 25-minute SSG sessions. Well-being indices were collected before each SSG-session. Heart rate was continuously measured throughout each session, and the ratings of perceived exertion and blood lactate concentration were collected after each SSG. A hierarchical cluster analysis was performed across variables and cases to identify associations between variables and variability in players' responses between sessions. No significant correlations were found between well-being indices, TQR and physiological parameters. Total quality recovery was positively correlated with successful pass % (r = 0.27) and interceptions (r = 0.25) and negatively correlated with lost balls (r = -0.25). Fatigue and DOMS were negatively correlated with tackles (r = -0.29, r = -0.28, respectively), successful pass % (r = -0.58, r = -0.55, respectively) and interceptions (r = -0.25, r = -0.27, respectively), and positively correlated with lost balls (r = 0.32, r = 0.28, respectively). Results provide an alternative and complementary method to understand training responses and can be an objective tool to help create subgroups in training for optimizing performance. This study demonstrates the efficacy and utility of using simple well-being and recovery measures to help coaches monitor athlete readiness.

Relationship between Indirect Measures of Aerobic and Muscle Power with Frequency Speed of Kick Test Multiple Performance in Taekwondo Athletes

This study aimed to determine the relationship between indirect measures of aerobic power and muscular power with Frequency Speed of Kick Test performance using multiple sets (FSKTmult) in high-level taekwondo athletes. We used a known-group method to test differences in FSKTmult performance between two groups designated as lower and higher performance in both aerobic power and muscular power. In total, 42 international or national taekwondo athletes of both sexes performed the FSKTmult, Progressive Specific Taekwondo Test (PSTT), and countermovement jump (CMJ). Our results showed that average of the three CMJ was moderately correlated with FSKTmult performance (r=0.44); whereas PSTT and FSKTmult were highly correlated (r=0.83). Moreover, the groups formed by lower and higher performance of time to exhaustion in PSTT, as well as the average of CMJ were able to discriminate performance in the FSKTmult (p ≤0.05). The present study thus suggests that aerobic and muscle power are important for FSKTmult performance.

Dose-Response Relationship Between Internal Training Load and Changes in Performance During the Preseason in Youth Soccer Players

ABSTRACT

Figueiredo, DH, Figueiredo, DH, Moreira, A, Gonçalves, HR, and Dourado, AC. Dose-response relationship between internal training load and changes in performance during the preseason in youth soccer players. J Strength Cond Res 35(8): 2294-2301, 2021-The aim of this study was to describe training intensity distribution based on the session rating of perceived exertion (sRPE) and heart rate (HR) methods and examine the dose-response relation between internal training load (ITL) and change in performance of 16 youth soccer players (mean ± SD age: 18.75 ± 0.68 years, height: 175.3 ± 5.5 cm, body mass: 68.7 ± 6.5 kg, and body fat: 10.7 ± 1.2%) belonging to a Brazilian first division team during a 3-week preseason. The sRPE and HR data were registered daily to calculate the ITL and the training intensity distribution, in 3 intensity zones (low, moderate, and high). The Yo-yo Intermittent Recovery Level 1 (Yo-yo IR1) was evaluated before and after experimental period. The total time spent in the low-intensity zone (HR method) was greater (p < 0.01) compared with the moderate- and high-intensity zones. No difference was observed between training intensity zones determined by the sRPE method (p > 0.05). Negative correlations were observed between weekly mean sRPE-TL (r = -0.69), Edward's-TL (r = -0.50), and change in Yo-yo IR1. Linear regression indicated that weekly mean sRPE-TL (F1;14 = 13.3; p < 0.01) and Edward's-TL (F1;14 = 4.8; p < 0.05) predicted 48.7 and 25.5% of the variance in performance change, respectively. Stepwise linear regression revealed that these 2-predictor variables (F2;13 = 18.9; p < 0.001) explained 74.5% of the variance in performance change. The results suggest that the sRPE and HR methods cannot be used interchangeably to determine training intensity distribution. Moreover, sRPE-TL seems to be more effective than the HR-based TL method to predict changes in performance in youth soccer players.

Intra-Season Variations in Workload Parameters in Europe's Elite Young Soccer Players: A Comparative Pilot Study between Starters and Non-Starters

Background: The main purpose of the current study was to compare the within-season variations of workload, training duration, acute/chronic workload ratio (ACWR), training monotony ™, and training strain (TS) through session rating perceived exertion (s-RPE) between starters and non-starters. Methods: Seventeen under-17 European male soccer players (age, 16.2 ± 0.3 y, height, 1.8 ± 0.1 m; body mass, 66.5 ± 4.0 kg) divided in two groups: nine starters and eight non-starters, were evaluated over 50 weeks throughout the season. Results: In general, there were load variations for all players during the full-season. RPE tended to decrease during in-season and RPE, training duration and s-RPE did not present significant differences between starters and non-starters. TM and TS presented lower values for starters in mesocycle (M) 4 and M11 compared to non-starters. TS presented lower values for starters in M4 and M11 compared to non-starters, while in M10 a higher value was found for starters when compared to non-starters. ACWR showed differences between starters and non-starters in two of the mesocycles. Conclusions: This study showed that some mesocycles provided higher load for non-starters. This information can alert coaches that non-starter players are likely to try too hard in training to demonstrate their abilities, leading to non-functional overreaching, overtraining syndrome, and then poor performance.

Effect of Kinesiology Tape on Tri-Axial Accelerometry During the Dance Aerobic Fitness Test

OBJECTIVES

Kinesiology tape (KT) is thought to provide greater mechanical support during physical activity, however, there is a paucity of research investigating its application in dance. The study aimed to determine whether KT reduces PlayerLoad (PL) during the Dance Aerobic Fitness Test (DAFT) in addition to examining the relative sensitivity of accelerometer site locations.

METHODS

University-level dancers (N = 11; age 18 ± 0.45 years, height 168.17 ± 12.25 cm, body mass 57.50 ± 9.91 kg) participated in two trials of the DAFT protocol in two conditions: no tape (NT) and kinesiology tape (KT). Global positioning systems (GPS) and accelerometer units were attached onto the seventh vertebra (C7) at the mid-scapula region and lower limb (LL) located at the mid-gastrocnemius of the dominant leg calculating measurements of triaxial (PLTotal) and uniaxial measures (anteroposterior [PLAP], mediolateral [PLML], and vertical [PLV]) measures of PlayerLoad during the DAFT.

RESULTS

No significant main effect was observed for the taping condition in all measures of PlayerLoad (P > 0.10). A significant main effect (p < 0.01) was observed for unit location and time, with greater loading at the LL compared to C7 and during each consequent stage of the DAFT. No significant (p > 0.52) location*taping, nor location*taping*time (p > 0.36) interactions were observed for all variables measured.

CONCLUSIONS

Kinesiology tape does not reduce loading patterns in healthy dancers during a fatigue protocol. However, triaxial accelerometers provide adequate sensitivity when detecting changes in loading, suggesting the LL may be deemed as a more relevant method of monitoring training load in dancers.

Quantifying Sub-Elite Youth Football Weekly Training Load and Recovery Variation

Monitoring the training load in football is an important strategy to improve athletic performance and an effective training periodization. The aim of this study was two-fold: (1) to quantify the weekly training load and recovery status variations performed by under-15, under-17 and under-19 sub-elite young football players; and (2) to analyze the influence of age, training day, weekly microcycle, training and playing position on the training load and recovery status. Twenty under-15, twenty under-17 and twenty under-19 players were monitored over a 2-week period during the first month of the 2019–2020 competitive season. Global positioning system technology (GPS) was used to collect external training loads: total distance covered, average speed, maximal running speed, relative high-speed running distance, high metabolic load distance, sprinting distance, dynamic stress load, accelerations and decelerations. Internal training load was monitored using ratings of perceived exertion (RPE) and session rating of perceived exertion (sRPE). Recovery status was obtained using the total quality recovery (TQR) scale. The results show an age-related influence for external training load (p ≤ 0.001; d = 0.29–0.86; moderate to strong effect), internal training load (p ≤ 0.001, d = 0.12–0.69; minimum to strong effect) and recovery status (p ≤ 0.001, d = 0.59; strong effect). The external training load presented differences between training days (p < 0.05, d = 0.26–0.95; moderate to strong effect). The playing position had a minimum effect on the weekly training load (p < 0.05; d = 0.06–0.18). The weekly microcycle had a moderate effect in the TD (p < 0.05, d = 0.39), RPE (p < 0.05; d = 0.35) and sRPE (p < 0.05, d = 0.35). Interaction effects were found between the four factors analyzed for deceleration (F = 2.819, p = 0.017) and between inter-day, inter-week and age for total covered distance (F = 8.342, p = 0.008). This study provided specific insights about sub-elite youth football training load and recovery status to monitor training environments and load variations. Future research should include a longer monitoring period to assess training load and recovery variations across different season phases.

Sex-specific effects of small-sided games in basketball on psychometric and physiological markers during Ramadan intermittent fasting: a pilot study

BACKGROUND

We assessed the effects of gender, in association with a four-week small-sided games (SSGs) training program, during Ramadan intermitting fasting (RIF) on changes in psychometric and physiological markers in professional male and female basketball players.

METHODS

Twenty-four professional basketball players from the first Tunisian (Tunisia) division participated in this study. The players were dichotomized by sex (males [G_M = 12]; females [G_F = 12]). Both groups completed a 4 weeks SSGs training program with 3 sessions per week. Psychometric (e.g., quality of sleep, fatigue, stress, and delayed onset of muscle soreness [DOMS]) and physiological parameters (e.g., heart rate frequency, blood lactate) were measured during the first week (baseline) and at the end of RIF (post-test).

RESULTS

Post hoc tests showed a significant increase in stress levels in both groups (G_M [- 81.11%; p < 0.001, d = 0.33, small]; G_F [- 36,53%; p = 0.001, d = 0.25, small]). Concerning physiological parameters, ANCOVA revealed significantly lower heart rates in favor of G_M at post-test (1.70%, d = 0.38, small, p = 0.002).

CONCLUSIONS

Our results showed that SSGs training at the end of the RIF negatively impacted psychometric parameters of male and female basketball players. It can be concluded that there are sex-mediated effects of training during RIF in basketball players, and this should be considered by researchers and practitioners when programing training during RIF.

Monitoring Training Load in Soccer: The ROMEI Model

Montini, M and Rocchi, JE. Monitoring training load in soccer: The Relation of Ongoing Monitored Exercise in Individual model. J Strength Cond Res 12XX(2X): 000-000, 2016. For a training organization, monitoring training load (TL) is of paramount importance. Despite this, a conclusive response on such topic is yet to be reported. The aims of this study were to investigate the relationship between TL indicators and to propose a new method for monitoring TL response and physical fitness. Twenty professional soccer players were retrospectively evaluated. The first phase of data analysis included 34 in-season training sessions. Subsequently, three microcycles (T1-T2-T3) of pre-season training were processed. A regression model was used to examine the relationships between internal TL (session rating of perceived exertion [s-RPE]) and external TL (energy expenditure, EE). The standard error of the regression equation was used to propose a new model called "ROMEI" (Relation of Ongoing Monitored Exercise in Individual). The level of statistical significance was set at p < 0.05. During the competitive season and the pre-season training camp, the average TL values were 65.8 ± 22 and 58.2 ± 22 minutes; 336 ± 204 and 228 ± 101 AU of s-RPE; and 29 ± 13 and 25 ± 9 kJ kJ of EE, respectively. In the competitive season, the collective and average individual correlation coefficients between s-RPE and EE were r = 0.888 and r = 0.892 ± 0.05, respectively. Considering slope values (m) of the regression line, data highlighted a significant increase of +34.4 ± 15.9% in T2 vs. T3 (p < 0.001) and +38.2 ± 15.2% in T1 vs. T3 (p < 0.001). Data shown in this investigation support the use of an individualized analysis to better understand the TL administered to soccer players rather than a collective analysis. This may be accomplished with the proposed ROMEI model.

Accelerometry as a method for external workload monitoring in invasion team sports. A systematic review

Accelerometry is a recent method used to quantify workload in team sports. A rapidly increasing number of studies supports the practical implementation of accelerometry monitoring to regulate and optimize training schemes. Therefore, the purposes of this study were: (1) to reflect the current state of knowledge about accelerometry as a method of workload monitoring in invasion team sports according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines, and (2) to conclude recommendations for application and scientific investigations. The Web of Science, PubMed and Scopus databases were searched for relevant published studies according to the following keywords: "accelerometry" or "accelerometer" or "microtechnology" or "inertial devices", and "load" or "workload", and "sport". Of the 1383 studies initially identified, 118 were selected for a full review. The main results indicate that the most frequent findings were (i) devices' body location: scapulae; (b) devices brand: Catapult Sports; (iii) variables: PlayerLoadTM and its variations; (iv) sports: rugby, Australian football, soccer and basketball; (v) sex: male; (vi) competition level: professional and elite; and (vii) context: separate training or competition. A great number of variables and devices from various companies make the comparability between findings difficult; unification is required. Although the most common location is at scapulae because of its optimal signal reception for time-motion analysis, new methods for multi-location skills and locomotion assessment without losing tracking accuracy should be developed.

Females Sustain more Ankle Injuries than Males in Youth Football

This prospective study evaluated the incidence and pattern of acute injuries in youth (9- to 14-year- old) football players. Ten football clubs [n=730 players (567 males, 163 females)] participated in the 20-week follow-up study (January-June 2015). Data was collected by sending a standardized weekly SMS to players' parents/guardians with follow-up interviews for injured players. During the study period, 278 players (38%) sustained 410 acute injuries. The overall injury incidence for males and females was 6.47 (95% CI, 5.84-7.09) injuries per 1000 h of football exposure. Most injuries (40%) caused minimal absence from sports. Eighty-four percent of the injuries affected the lower extremities, with the ankle (30%), knee (17%), and thigh (16%) being the most commonly injured body sites. Females had significantly higher ankle injury rate (IRR) 1.85 (95% CI, 1.18-2.91, p=0.007) and non-contact ankle injury rate IRR 2.78 (95% CI, 1.91-4.02, p<0.001) than males. In conclusion, our results showed that the acute injury incidence among youth football is moderately high, and females are at higher risk for ankle injuries. Injury prevention programs aimed at preventing ankle injuries should be considered in the future.

Stress and recovery perception, creatine kinase levels, and performance parameters of male volleyball athletes in a preseason for a championship

Background

Training load and adequate recovery have been identified as essential elements to improve well-being and performance in team sports and avoid non-functional overreaching and overtraining.

Objective

This cohort study sought to analyze the stress and recovery perceptions, creatine kinase levels (CK), and vertical jump performance of volleyball athletes at different training times during a championship preseason.

Methods

Thirteen high-level male volleyball players (23.80 ± 5.40 years, 91.50 ± 8.80 kg, and 193.10 ± 6.40 cm) completed the RESTQ-Sport questionnaire on stress and recovery perception, and blood samples were collected to evaluate CK levels. These measures were performed six times over 16 weeks, while jumps such as squat jump (SJ), countermovement jump (CMJ), and countermovement jump arm (CMJA) were performed at three of those times for specific performance evaluation.

Results

The stress perception and recovery perception indices increased and decreased, respectively, in the pre-competitive phase, while CK levels presented an initial rise, maintenance over the training period, and a drop. Vertical jump heights increased significantly throughout the preparatory period regardless of the type of jump. In all training phases, CMJA values exceeded CMJ and SJ values, and CMJ values exceeded SJ values.

Conclusions

Positive adaptations were elicited by training stimuli, resulting in improvements in performance. Conversely, load training variables indicated higher levels of stress and muscle damage, together with lower perceptions of recovery during the championship preseason.

Seasonal Training Load Quantification and Comparison in College Male Soccer Players

Ryan, GA, Snarr, RL, Eisenman, ML, and Rossi, SJ. Seasonal training load quantification and comparison in college male soccer players. J Strength Cond Res XX(X): 000-000, 2020-Monitoring and quantification of training load (TL) throughout a competitive soccer season is important to ensure players are able to perform throughout the season. The intent of this study was to examine the positional demands and patterns of select measures of TL during a 14-week season in collegiate male soccer players. Heart rate (HR), running performance (SZ), and perceived recovery data were collected daily using a bioharness for each subject (n = 21). Data were grouped into 2- to 3-week training blocks (Pre1, Pre2, In1, In2, In3, and In4). Continuous variables were analyzed using a multivariate analysis of variance, with post hoc Least Squared Difference pairwise comparisons. Significant positional differences were observed across the season. During Pre1, center midfielders (CM) spent more time in %HRlow compared to center backs (CB) (p < 0.01), wide midfielders (p < 0.01), and center forwards (p = 0.04). Center midfielders spent greater time in SZlower than CB (p < 0.01) and wide backs (WB) (p = 0.01). Wide backs spent greater time in SZupper compared to other positions (all p < 0.01). During Pre2, WB spent more time in %HRhigh and SZupper compared to other positions (all p < 0.01). Positional differences were more varied throughout in-season comparisons, but generally, WB and CB demonstrated higher intensities in variables compared to other positions. Tracking variations in positional TLs across the season is important for coaching and training staffs to determine player readiness and plan future training sessions, while helping to mitigate overuse injuries during a long competitive season.

Quantification of the Perceived Training Load in Young Female Basketball Players

Otaegi, A and Los Arcos, A. Quantification of the perceived training load in young female basketball players. J Strength Cond Res 34(2): 559-565, 2020-The purposes of this study were (a) to compare training session, match, and weekly perceived training load (TL) between U15 and U16 female basketball players and (b) within the teams, to assess the relationship between perceived TL and the changes in physical fitness performance during an in-season 9-week period. Twenty-one female players from U15 and U16 female teams from the same Spanish club participated in the study. Before and after the study, players were tested to determine physical fitness performance (using Yo-Yo IR1, countermovement jump, T-Test, and 15 m sprint). Each player declared her perceived exertion (PE) for the whole training session and match using Foster's 0-10 scale. Training week perceived TL was higher for the U16 players than the U15 players; U16 players considered the training and matches to be more difficult. In both teams, the perceived TL of the last training session of the week was significantly lower (Effect sizes = large-very large) than the other sessions. Although substantial negative associations (r = 0.52-0.78) were detected between the changes in physical fitness performance and the accumulated volume, sum of PEs and perceived TL in the U15 players, these associations were unclear in the U16 players. The basketball coaches-periodized training goals are to attain the highest session perceived TLs in the middle of the week and to reduce it considerably in the last training session. The U16 and U15 players accumulated perceived TL in different ways. Although the practice volume was similar in both teams, the older players consider the sessions more difficult. The relationship between the perceived TL and the changes in physical fitness performance varied between teams. Based on our findings, we propose that the PE-based dose-response model should be applied with caution in young female basketball players.

Field-Based Tests for the Assessment of Physical Fitness in Children and Adolescents Practicing Sport: A Systematic Review within the ESA Program

High levels of physical fitness (PF) can positively affect both health and cognitive function, thus monitoring its levels in youth can help increase health and quality of life in adult populations later on. This systematic review aims to identify PF field-based tests used in young European populations practicing sport to find tools that are adequate for the considered target involving a new battery within the Enriched Sport Activities (ESA) project. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was followed. In the 83 identified articles, the main tests used were: vertical/horizontal jumps (for muscular strength/power); push-ups, running at maximum effort, sit-ups (for muscular strength/endurance); multistage non-intermittent and intermittent tests (for aerobic endurance); sit and reach (for flexibility); sprinting and agility T-tests (for speed and agility, respectively); 10 × 5 m shuttle run (SR) (for both speed and agility). Few studies assessed coordination, reaction time, power, and balance. Although the selected tests are widely used and validated, they do not determine all PF aspects and do not reflect sport-specific features. A final decision was made for the inclusion of the following tests: standing broad jump, seated medicine ball throw, 20 m SR test, 30 m sprint, Illinois test, and a new test, i.e., the crunning test, to assess different skill-related components at once. The use of this combination of tests allows for the assessment of all PF components and can help planning effective training programs and cultivate sporting talent.

Patellar tendon structure responds to load over a 7-week preseason in elite male volleyball players

The purpose of this study was to investigate the relation between external and internal load and the response of the patellar tendon structure assessed with ultrasound tissue characterization (UTC) in elite male volleyball players during preseason. Eighteen players were followed over 7 weeks, measuring four load parameters during every training and match: volume (minutes played), rating of perceived exertion (RPE) (ranging from 6 to 20), weekly load (RPE*volume), and jump frequency (number of jumps). Patellar tendon structure was measured biweekly using UTC, which quantifies tendon matrix stability resulting in four different echo types (I-IV). On average, players spent 615 min/wk on training and matches with an RPE of 13.9 and a jump frequency of 269. Load evaluation shows significant changes over the 7 weeks: Volume and weekly load parameters were significantly higher in week 3 than week 7 and in week 4 than week 2. Weekly load performed in week 4 was significantly higher than week 7. No significant changes were observed in tendon structure. On the non-dominant side, no significant correlations were found between changes in load parameters and echo types. At the dominant side, a higher weekly volume and weekly load resulted in a decrease of echo type I and a higher mean RPE in an increase of echo type II. The results of this study show that both external and internal load influence changes in patellar tendon structure of elite male volleyball players. Monitoring load and the effect on patellar tendon structure may play an important role in injury prevention.

MONITORING TRAINING LOAD AND RECOVERY IN VOLLEYBALL PLAYERS DURING A SEASON

ABSTRACT Introduction Monitoring training loads, along with the recovery status, is important for preventing unwanted adaptations. Knowledge of these variables over volleyball seasons is still scarce. Objective To monitor and describe the training load and recovery status of volleyball players over a competitive season. Methods The sample consisted of 14 professional volleyball players. For the entire season, the training load was monitored daily by the SPE method during the session, and the recovery status was monitored by TQR and QBE on the first and last days of training for the week. Results There was a decrease in training load between Preparatory Period I and Competitive Period I (p = 0.03), followed by an increase in Preparatory Period II (p <0.001) and a new decrease in Competitive Periods II (p = 0.01 ) and III (p = 0.003). There was a significant reduction between Pre-TQR and QBE and Post-TQR and QBE in all mesocycles. In the Pre-TQR, there was a reduction between Preparatory Period II and Competitive Period II (p = 0.006), in the Pre-QBE, there was a reduction between Preparatory Period II and Competitive Period III (p = 0.002), and in the Post-TQR, this reduction was observed between Competitive Period I and Preparatory Period II (p = 0.03). In the Post-QBE, there was an increase between Preparatory Period I and Competitive Period I (p = 0.002), followed by a decrease in Preparatory Period II (p = 0.01). Conclusion Loads varied throughout the season, along with recovery, which varied according to the loads and characteristics of each period. Level of evidence I, Therapeutic Studies – Investigating the Results of Treatment.

The team's influence on physical and technical demands of elite goalkeepers in LaLiga: a longitudinal study in professional soccer

This study examined physical and technical demands and the influence of the team's level on elite goalkeepers' performance during six consecutive seasons in Spanish Professional Soccer League. The goalkeepers' performance data were obtained by analyzing a total of 3,874 matches using a multiple-camera computerized tracking system. The physical and technical match variables registered were: distance traveled; distance Sprinted and the number of sprints; total number of passes; successful passes; pass percentage; recovered balls; lost balls; ratio lost balls: recovered balls, and number of saves. The results showed that the number of saves made has shown a significant reduction (p < 0.001). When comparing between the teams' level, the goalkeepers of the worst classified teams showed a greater distance traveled by sprint (+3.72 m, IC95%: 1.00-6.44, ES: 0.41, p = 0.008). In conclusion, the results the influence of the team's level on the technical and physical parameters of the goalkeepers during the last six seasons.

Getting the most out of intensive longitudinal data: a methodological review of workload-injury studies

OBJECTIVES

To systematically identify and qualitatively review the statistical approaches used in prospective cohort studies of team sports that reported intensive longitudinal data (ILD) (>20 observations per athlete) and examined the relationship between athletic workloads and injuries. Since longitudinal research can be improved by aligning the (1) theoretical model, (2) temporal design and (3) statistical approach, we reviewed the statistical approaches used in these studies to evaluate how closely they aligned these three components.

DESIGN

Methodological review.

METHODS

After finding 6 systematic reviews and 1 consensus statement in our systematic search, we extracted 34 original prospective cohort studies of team sports that reported ILD (>20 observations per athlete) and examined the relationship between athletic workloads and injuries. Using Professor Linda Collins' three-part framework of aligning the theoretical model, temporal design and statistical approach, we qualitatively assessed how well the statistical approaches aligned with the intensive longitudinal nature of the data, and with the underlying theoretical model. Finally, we discussed the implications of each statistical approach and provide recommendations for future research.

RESULTS

Statistical methods such as correlations, t-tests and simple linear/logistic regression were commonly used. However, these methods did not adequately address the (1) themes of theoretical models underlying workloads and injury, nor the (2) temporal design challenges (ILD). Although time-to-event analyses (eg, Cox proportional hazards and frailty models) and multilevel modelling are better-suited for ILD, these were used in fewer than a 10% of the studies (n=3).

CONCLUSIONS

Rapidly accelerating availability of ILD is the norm in many fields of healthcare delivery and thus health research. These data present an opportunity to better address research questions, especially when appropriate statistical analyses are chosen.

Monitoring Training Load, Recovery, and Performance of Brazilian Professional Volleyball Players During a Season

Purpose: To describe and analyze the distribution of internal training load (ITL), recovery, and physical performance of professional volleyball players throughout 1 season. Methods: Fifteen male professional Brazilian volleyball players participated in this study. The session rating of perceived exertion (s-RPE) and Total Quality Recovery (TQR) score were collected daily for 36 wk. s-RPE was collected after each training session, and TQR, before the first session of the day. The sum of the ITL of each session during the week, training monotony, strain, acute∶chronic workload ratio, match difficulty score, and average of the TQR scores were recorded for the analysis. In addition, the athletes performed countermovement-jump (CMJ) tests with and without the use of the arms 4 times over the season. Results: The season mean weekly ITL was 3733 (1228) AU and the TQR was 15.02 (0.71). The ITL and recovery demonstrated undulating dynamics over the 36 wk, with higher weekly ITL in the preparatory periods (F = 50.32; P < .001) and worse recovery during the main competition (F = 6.47; P = .004). Negative correlations were found between TQR and ITL variables (P < .05). There was improvement and maintenance in CMJ tests without (F = 11.88; P < .001) and with (F = 16.02; P < .001) the use of the arms after the preparatory periods. Conclusions: The ITL variables, recovery, and physical performance changed significantly throughout a professional volleyball season. Despite the decrease in ITL during the main competitive period, the correct distribution of weekly ITL seems to be very important to guarantee the best recovery of athletes.

Different Training Loads Partially Influence Physiological Responses to the Preparation Period in Basketball

Ferioli, D, Bosio, A, La Torre, A, Carlomagno, D, Connolly, DR, and Rampinini, E. Different training loads partially influence physiological responses to preparation period in basketball. J Strength Cond Res 32(3): 790-797, 2018-The aim of this study was to compare the session rating of perceived exertion training load (sRPE-TL), training volume (TV), and the changes in physical fitness between professional (n = 14) and semiprofessional (n = 18) basketball players during the preparation period. Furthermore, relationships between sRPE-TL and TV with changes in physical fitness level were investigated. The players performed the Yo-Yo intermittent recovery test-level 1 (Yo-Yo IR1) before and after the preparation period. In addition, physiological responses to a standardized 6-minute continuous running test (Mognoni's test) and to a standardized 5-minute high-intensity intermittent running test (HIT) were measured. Session rating of perceived exertion-TL and TV were greater for professional (5,241 ± 1787 AU; 914 ± 122 minutes) compared with semiprofessional players (2,408 ± 487 AU; 583 ± 65 minutes). Despite these differences, Yo-Yo IR1 performance improvements (∼30%) and physiological adaptations to the Mognoni's test were similar between the 2 groups. Furthermore, physiological adaptations to HIT were slightly greater for professional compared with semiprofessional players; however, the magnitude of these effects was only small/moderate. No clear relationships were found between sRPE-TL and changes in Yo-Yo IR1 performance and Mognoni's test (rs ± 90% confidence interval [CI]: Yo-Yo IR1, 0.18 ± 0.30; Mognoni's test, -0.14 ± 0.29). Only moderate relationships were found between sRPE-TL and changes in HIT (rs ± 90% CI: [La], -0.48 ± 0.23; [H], -0.42 ± 0.25). These results raise doubts on the effectiveness of using high sRPE-TL and TV during the preparation period to improve the physical fitness level of players. The Yo-Yo IR1 seems to be sensitive to monitor changes induced by the preparation period; however, its use is not recommended to discriminate between adult basketball players of different competitive level.

Perceived training load and jumping responses following nine weeks of a competitive period in young female basketball players

The aims of this study were to describe the session rating of perceived exertion (sRPE), total quality recovery (TQR), and variations in countermovement jump (CMJ) height throughout nine weeks of a competitive period in young female basketball players. In total, 10 young female basketball players (17.2 ± 0.4 years; 71.8 ± 15.0 kg; 177.2 ± 9.5 cm) participated in this study. The sRPE and TQR were assessed in each training session, whereas the CMJ height was assessed prior to the first weekly training session. The magnitude-based inferences method was used to compare the sRPE, TQR, and CMJ height across the nine weeks of training. The training loads accumulated in weeks 1, 2, and 3 were likely to almost certainly be higher than in the following weeks (ES varying from 0.67 to 2.55). The CMJ height in week 1 was very likely to be lower than in weeks 2, 5, 7, and 8 (ES varying from 0.24 to 0.34), while the CMJ height of the 9th week was likely to almost certainly be higher than all previous weeks of training (ES varying from 0.70 to 1.10). Accordingly, it was observed that when higher training loads were accumulated, both CMJ and TQR presented lower values than those presented during periods with lower internal training loads. These results highlight the importance of using a comprehensive and multivariate approach to effectively monitor the physical performance of young athletes.

Relationships Between Training Load Indicators and Training Outcomes in Professional Soccer

BACKGROUND

In professional senior soccer, training load monitoring is used to ensure an optimal workload to maximize physical fitness and prevent injury or illness. However, to date, different training load indicators are used without a clear link to training outcomes.

OBJECTIVE

The aim of this systematic review was to identify the state of knowledge with respect to the relationship between training load indicators and training outcomes in terms of physical fitness, injury, and illness.

METHODS

A systematic search was conducted in four electronic databases (CINAHL, PubMed, SPORTDiscus, and Web of Science). Training load was defined as the amount of stress over a minimum of two training sessions or matches, quantified in either external (e.g., duration, distance covered) or internal load (e.g., heart rate [HR]), to obtain a training outcome over time.

RESULTS

A total of 6492 records were retrieved, of which 3304 were duplicates. After screening the titles, abstracts and full texts, we identified 12 full-text articles that matched our inclusion criteria. One of these articles was identified through additional sources. All of these articles used correlations to examine the relationship between load indicators and training outcomes. For pre-season, training time spent at high intensity (i.e., >90 % of maximal HR) was linked to positive changes in aerobic fitness. Exposure time in terms of accumulated training, match or combined training, and match time showed both positive and negative relationships with changes in fitness over a season. Muscular perceived exertion may indicate negative changes in physical fitness. Additionally, it appeared that training at high intensity may involve a higher injury risk. Detailed external load indicators, using electronic performance and tracking systems, are relatively unexamined. In addition, most research focused on the relationship between training load indicators and changes in physical fitness, but less on injury and illness.

CONCLUSION

HR indicators showed relationships with positive changes in physical fitness during pre-season. In addition, exposure time appeared to be related to positive and negative changes in physical fitness. Despite the availability of more detailed training load indicators nowadays, the evidence about the usefulness in relation to training outcomes is rare. Future research should implement continuous monitoring of training load, combined with the individual characteristics, to further examine their relationship with physical fitness, injury, and illness.

Functional Movement Screen Scores and Physical Performance among Youth Elite Soccer Players

This study had two main objectives: (1) to determine if differences in Functional Movement Screen (FMS) scores exist between two levels of competition; and (2) to analyze the association between FMS individual and overall scores and physical performance variables of lower-limb power (jumps), repeated sprint ability and shot speed. Twenty-two Under 16 (U16) and twenty-six Under 19 (U19) national competitive soccer players participated in this study. All participants were evaluated according to anthropometrics, FMS, jump performance, instep kick speed and anaerobic performance. There were no significant differences in the individual FMS scores between competitive levels. There were significant negative correlations between hurdle step (right) and Running-based Anaerobic Sprint Test (RAST) power average (ρ = −0.293; p = 0.043) and RAST fatigue index (RAST FatIndex) (ρ = −0.340; p = 0.018). The hurdle step (left) had a significant negative correlation to squat jump (SJ) (ρ = −0.369; p = 0.012). Rotary stability had a significant negative correlation to RAST fatigue index (Right: ρ = −0.311; p = 0.032. Left: ρ = −0.400; p = 0.005). The results suggest that individual FMS scores may be better discriminants of performance than FMS total score and established minimal association between FMS scores and physical variables. Based on that, FMS may be suitable for the purposes of determining physical function but not for discriminating physical performance.

Descriptive analysis of objectively assessed physical activity among talented soccer players: a study of three Norwegian professional football clubs

BACKGROUND

Talented football players are expected to overcome large training and match loads, indicating a high weekly level of physical activity (PA).

AIMS

With the use of accelerometers, the aim of this study was to objectively describe the players' total time spent in moderate-to-vigorous PA (MVPA), vigorous PA (VPA) and very vigorous PA (VVPA) per day in 1 week. Since high-intensity PA has been highlighted as important in terms of overall PA load, we also included 2 and 4 min bouts of VPA.

METHODS

Data were collected in three junior teams in professional football clubs in March (club 1: 2014, club 2: 2012 and club 3: 2011). A one-way analysis of variance was applied to analyse differences between the three respective clubs.

RESULTS

The players averaged 77.2-86.2 min in MVPA, 14.9-18.5 min in VPA and 1.0-3.1 in VVPA per day. While there were no differences in total time spent in MVPA and VPA per day, VVPA was significantly higher in club 1 (p<0.01) compared with clubs 2 and 3. Moreover, when using the VPA bouts, club 3 (p<0.01) achieved significantly more time in this intensity compared with clubs 1 and 2.

CONCLUSION

This study acknowledges the importance of including both club-related and non-club-related PA when analysing talented football players' PA level. We suggest that future studies examining players' PA with accelerometers should emphasise time spent in high-intensity PA and how this is associated with physical overload, psychological burnout and risk of injury.

Content Validation of a Catalog of Exercises for Judo

This study aimed to assess the content validity of a catalog of 76 judo exercises. Two groups of raters comprising 16 judo experts evaluated the following content validity indicators: Clarity of Language, Practical Pertinence, Theoretical Relevance, and the Dimension of each exercise. The results confirmed the content validity of the judo training catalog with indicators showing scores greater than 0.80. These findings suggest that all 76 judo exercises are pertinent, representative of judo training and understandable for judo coaches. Thus, this catalog of judo exercises may help judo coaches in the selection and recording of exercises.